The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere-sea ice-ocean model

The relatively warm early Holocene climate in the Nordic Seas, known as
the Holocene Thermal Maximum (HTM), is often associated with an
orbitally forced summer insolation maximum at 10 ka BP.
The spatial and temporal response recorded in proxy data in the North
Atlantic and the Nordic Seas reveal a complex interaction of mechanisms
active in the HTM.
Previous studies have investigated the impact of the Laurentide Ice
Sheet (LIS), as a remnant from a previous glacial period, altering
climate conditions with a continuous supply of melt water to the
Labrador Sea and adjacent seas and with a downwind cooling effect from
the remnant LIS.
In our present work we extend this approach by investigating the impact
of the Greenland Ice Sheet (GIS) on the early Holocene climate and the
HTM.
Reconstructions suggest melt rates of 13 mSv for 9 ka BP, which result
in our model in a ocean surface cooling of up to 2 K near Greenland.
Reconstructed summer SST gradients agree best with our simulation
including GIS melt, confirming that the impact of early Holocene GIS is
crucial for understanding the HTM characteristics in the Nordic Seas
area.
This implies that the modern and near-future GIS melt can be expected to
play an active role in the climate system in the centuries to come.